The Ribosome in Action

Proteins, one of the basic building blocks of cells, are synthesized by linking amino acids together in macromolecular factories called ribosomes. The 20,000 ribosomes in a bacterial cell translate messenger RNA (mRNA) with remarkable speed and accuracy, and two articles in this issue provide fascinating new insights into how this is achieved. These publications come at a time of rapid progress in structural studies of the ribosome. Within the past year both the 30S and 50S subunit structures have been determined at atomic resolution (1-3); the large subunit (50S) and the small subunit (30S) comprise the whole ribosome (70S). Unlike previous reports, however, Noller, Ramakrishnan, and their co-workers have now more closely approximated the functional state of the ribosome by including transfer RNA (tRNA) and mRNA in their crystals, thus providing views of the ribosome in action.